This invention relates to power door lock apparatus for motor vehicle doors, and particularly to such apparatus which is electrically controlled and pneumatically powered. Such a system has potential advantages in quietness and weight over all electric systems, especially if a large number of door locking or releasing mechanisms are included.
A typical such system is required to lock and unlock, from a single switch, all passenger doors. In addition, such a system should be capable of separately unlocking or releasing auxiliary doors such as the trunk or deck lid and the fuel filler door. Such a system may use a single bidirectional electric motor driven pump which generates vacuum driven one way and positive pressure above atmosphere when driven in the opposite direction. The pressure or vacuum from the pump is admitted by solenoid valves to pneumatic lines connected to the various actuators. Such a system should coordinate the operation of the pump and solenoids to prevent the inadvertent operation of one type of mechanism when another conflicting operation is started but allow override of one type of operation by another when desired. For example, if an action involving vacuum is in progress, the system should prevent the generation of positive pressure in the lines unless this is required by a later initiated overriding operation, in which case the system must first stop the vacuum production. As another example, a driver wishing to unlock the doors for his passengers does not necessarily wish to release the fuel filler latch and have the fuel filler door spring open; but he may wish to do the latter at a different time without unlocking the passenger doors.
The prior art in electropneumatic door lock systems is generally of the type shown in U.S. Pat. No. 3,096,112 to Johnstone, issued July 2, 1963, in which all door lock or release actuators are pneumatically connected in common to the pump to be locked or unlocked together. Similar systems are shown in U.S. Pat. No. 4,468,942 to Grabner et al, issued Sept. 4, 1984, U.S. Pat. No. 4,253,319 to Feichtiger et al, issued Mar. 3, 1981, U.S. Pat. No. 4,466,263 to Rathmann, issued Aug. 21, 1984, U.S. Pat. No. 4,181,191 to Hoffmann et al, issued Jan. 1, 1980, and U.S. Pat. No. 3,111,184 to Oishei, issued Nov. 19, 1963. U.S. Pat. No. 2,888,287 to Taylor, issued May 26, 1959, shows a variation in that the pneumatic lines to the four passenger doors are each controllable by a manually operated valve to be left out of the common actuation. However, none of these examples of the prior art allows selective independent power activation of a passenger door and and auxiliary door such as a trunk lid or fuel filler door with circuitry preventing non-desired activations but allowing override of an earlier, unfinished operation by a later initiated conflicting operation.